Pathology of thyroid malignancies

Mohit kadyanRoll no:26

Carcinomas

Papillary carcinoma (>85% os cases)

Follicular carcinoma (5 to 15% of cases)

Medullary carcinomas (5% of cases)

Anaplastic carcinomas(<5%) of cases)

Most thyroid carcinomas (except medullary carcinomas) are derived from the thyroid follicular epithelium and are well differentiated lesions.

Medullary carcinomas are derived from parafollicular cells or “ C” cells.

Papillary carcinoma Commonest form of thyroid carcinoma

Can occur at any age but more often seen in 25 to 50 yrs of age

Commonest form associated with radiation exposure

Metastasis via lymphatics

Excellent prognosis with 10yr survival rate in 95% patients

Morphology

Solitary or multifocal lesions

It can be soft, cystic, hard, firm.

Well circumscribed & encapsulated.

Cut surface reveals papillae

Histology

The nuclei appear optically clear, giving rise to “ ground glass appearance”

It shows cystic spaces , papillary projections with psammoma bodies

Malignant cells shows invaginations of cytoplasm in nuclei “ Orphan annie eye” (pseudo-inclusions)

Orphan annie eyes

Follicular carcinoma Common in women (3:1) & present at

older age than papillary carcinoma.

Peak incidence in 40 t0 60 yrs of age.

More incidence in areas with dietary iodine deficiency

Metastasise through blood to lungs , bone &liver. Prognosis is poorer than papillary Ca.

Morphology Histology Single nodules,

may be well circumscribed or infiltrative

Gray to tan on cut section and translucent due to colloid filled follicles

Uniform cells form small follicles containing colloid.

Sometimes differentiation is less. Nests and sheets of cells & no colloid.

Hurthle cell carcinoma

Is a varient of follicular carcinoma of thyroid which contains abundant oxyphill cells

Medullary carcinoma

Neuroendocrine neoplasm derived from parafollicular cells ,”C” cells.

Secrete calcitonin –helpful in diagnosis & follow-up.

They are aggressive and metastasise more frequently.

Morphology Histology

Solitary nodules Large lesions contain

areas of hemorrhage and necrosis

Tumor tissue is firm, pale, gray to tan and infiltrative.

Composed of polygonal to spindle shaped cells, which form nests , trabaculae and even follicles.

Acellular amyloid deposits are present.

Anaplastic(undifferentiated) Ca One of the most aggressive malignancies

Found in elderly , rare , less than <5%

Metastasis is common, through lymphatics &blood

Death is usually from rapid from aggressive local growth

Mortality is 100%

Morphology

Large solid tumour with necrosis & hemorrhage that invades surrounding structures

Histology

Composed of highly anaplastic cells , includes

Pleomorphic giant cells Spindle cells Mixed spindle and giant cells

Points to be noted..

Solitary nodules are more likely to be neoplastic than multiple nodules.

Nodules in younger patients are more likely to be neoplastic than those in elder.

Nodules in males are more likely to be neoplastic than are those in females.

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